Centrifuge with primary and secondary zones of separation and process therefor



Oct. 18, 1949. L J. LUNDAL 2,485,209

CENTRIFUGE WITH PRIMARY AND SECONDARY ZONES OF SEPARATION AND PROCESS THEREFOR Filed July 16, 1943 6 35 I U /9 I9 20 20 32 6 a 5%; L I 132 34 :I i 33 6 I? 33 'JQ 34 I7 r' Z2 5 i ,5 ,3 a9 1 a9 "Il M 4 i v H /4 67a F 25 57a 36 38 INVENTORQ In Se d'LandaL 8Y UNITED STATES PATENT OFFICE CENTRIFUGE WITH PRIIHARY AND SECOND- ARY ZONES OF SEPARATION AND PROC- ESS THEREFOR Ingie J. Lundal, Chicago, Ill., assignor, by direct and mesne assignments, to Sugar Creek Creamery Company, Danville, 11]., a corporation of Delaware, and Cherry-Burrell Corporation, Chicago, Ill., a corporation oi Delaware, as joint owners Application July 16, 1943, Serial No. 494,966

22 Claims. 1

This invention relates to centrifugal devices and processes. More particularly, this invention relates to improvements in centrifugal devices and processes for the separation and concentration of various separable fractions of liquids, such,

fat and skim-milk are normally discharged into appropriate collectors.

In the normal operation of the conventional type of centrifugal milk or cream separator and concentrator for the separation of sour cream, all

for example, as the separable fractions of sour 5 of the product to be separated or concentrated, cream, i. e., concentrated butter fat, skim-milk together with any extraneous foreign matter, as and coagulated protein. well as coagulated protein which is commonly In the separation and concentration of cream, found in sour cream, is discharged from the inparticularly sour cream, through the use of the feed or primary separation chamber into the lamconventional type of centrifugal cream separator, inar spaces intermediate the stratifying or sepathe efliciency of the separator is generally imrating-disks in the outer centrifugal or final seppaired by the accumulation within the various aration chamber. The separated extraneous matportions of the centrifugal rotary separator eleter and concentrated coagulated protein comments of sufiicient quantities of coagulated promonly accumulates in the .outer peripheral spaces tein and entrapped extraneous matter, including of the primary separation chamber and in-bethe products .of neutralization, to bring about a tween the stratifying disks from which it is norl'estriction'of the free flow of the liquids through mally not removable during the operation of the the separation device, resulting in the decreased separating and concentrating device.

. operating efliciency. Such accumulation of co- The rotation of the primary and secondary agulated proteins and entrapped entraneous matcentrifugal separating chambers brings about the ter is most commonly found intermediate the separation and concentration of the butter fat separating or stratifying disks and in the outer from the skim-milk and coagulated protein and peripheral portions of the centrifugal rotor. These other heavier extraneous matters. The skimaccumulations may, if the separation process conmilk and coagulated protein and other heavier tinues for a sufficient period .of time, completely extraneous matters pass outwardly through-beobstruct the flow of liquid through the separating tween the stratifying disks to the outer peripheral device, necessitating the discontinuance of the portions of the final or secondary separating operation and cleaning of the separator. chamber while the concentrated cream or butter In the conventional cream separator of the cenfat passes inwardly between the stratifying disks trifugal bowl or rotar type, the milk or cream to toward the axis of rotation. be separated is normally introduced into the bowl Foreign matters, such as are commonly found through an infeed or primary centrifugal separain milk or sour cream, particularly coagulated tion chamber in which the milk or cream is subproteins, have a tendency to adhere to and acjected to primary centrifugal separation. The cumulate upon the surfaces of the stratifying milk or cream is normally discharged from the disks and, after a short period of operation of primary separation chamber into a final centrifthe centrifugal separator, also to completely obugal separation chamber in which it is most comstruct the flow through the spaces intermediate monly divided into laminae intermediate a suitthe stratifying disks of the liquid to be separated able number of stratifying or separating disks. 0 and concentrated. In certain instances these ac- Substantially all of the final separation of butter cumulations also obstruct the fiow of the product fat or concentrated cream from the milk or diin the outer peripheral portions of the final sepaluted cream and the concentration of thebutter ration chamber. When either of such obstructions fat take place in the laminar divisions of the milk occurs it is necessary to discontinue the separaor cream. The separated and concentrated cream tion operation, disassemble the separating device or u ter fat and he Skim-m lk are n rmally diS- and remove the accumulations of coagulated pro- ,c a d sep r ely rom e fi separation teins and foreign matters from the obstructed chamber through axial overflow ducts extending flo spaces, through the pp a l Of 171190111381 c gal The primary objects of the present invention rotor, from which ducts the concentrated butter are, therefore, to provide novel and inexpensive the process of centrifugally separating and concentrating separable fractions of liquids, whereby the accumulation of material within the centrifugal separating device is prevented. More particularly, the objects of the present invention, as applied to the preferred embodiment and method of operation thereof, are to provide a device and process in which the free flow through the centrifugal separator of the liquid, such as cream, being separated and concentrated is not obstructed by the accumulation of materials, such as coagulated proteins and other extraneous matters, and the overall efiiciency of the operation of the separating device is improved.

The objects of the present invention with respect to the centrifugal separating device, as illustrated in the drawing, relate to the provision of improvements for the free passage of concentrated flow obstructing materials, such as coagulated protein and other foreign matter, from the primary separating chamber into the outer and final or secondary separating chamber and the discharge of such materials from the separating chambers without impairing the efficiency of the device in the separation of liquids, such as, for example, the separation of butter fat from skim-milk and in the concentration of the separated butter fat.

The foregoing and other objects of the present invention will become more apparent as the nature of the invention is hereinafter more fully explained. The preferred embodiment of the structural features of the present invention and the details of the improved process and method of operation will be best understood from the following description when read in connection with the accompanying drawing. In the drawing there is shown a vertical cross sectional view of an improved centrifugal cream separator and concentrator embodying the structural improvements according to the present invention and adapted for use in the practice of the improved process.

In the drawing, in which like numerals are used to identify like elements, It represents a support and drive shaft driven by any suitable source of power (not shown). Shaft in has a tapered end for extension into a complementary and substantially conical hollow spindle formed integrally I with the lower wall |2 of the outer centrifugal separator rotor or bowl |3 which is supported by and nicely balanced upon and driven by the shaft l0 through a suitable driving connection of conventional design.

The outer wall of the centrifugal bowl or rotor .|3, the maximum diameter of which is approximately centrally thereof, 1. e., approximately midway between its upper and lower extremities is formed of opposed frusto-conical surfaces l4 and i5. The upper wall of the outer rotor |3 consists of a frusto-conical section I6 preferably secured to the wall portion II by a screw-threaded coupling I! of suitable design. The upper wall I6 is provided with an annular .upwardly extending neck l3 which is partially closed by a ring dam l9 secured thereto by a screw coupling 20.

Extending downwardly through the neck l8 and co-axially with the outer bowl l3 there is provided a hollow centrally positioned infeed tube 2| having a downwardly and outwardly expanded wall. The expanded wall 2 I, at approximately the mid-portion of the outer and final or secondary lower end of the tube 2| to thereby define a first of primary separation chamber. Wall section 23, together with an integrally formed flange 24 and the lower, wall l2 of the outer rotor l3, more specifically stated define the outer wall of a primary or first separation chamber 25. The outer peripheral wall of the secondary separation chamber 22 surrounds the primary separation chamber 25 and extends substantially beyond the outer periphery of the primary separation chamber 25.

The. combined hollow infeed tube 2| and the expanded wall 23 are seated by means of the ring flange 24 on the lower wall l2 of the outer rotor l3 and are maintained in spaced co-axial position by the ledge 23 in the lower wall l2, which ledge is telescoped into flange 24. The infeed tube 2| and the wall 23 are rotated co-axially with the outer rotor l3 by means of the driving key 21 appropriately interposed between the fiange 24 and the ledge 26.

Formed integrally with the inner wall of the infeed tube 2| and extending lengthwise and inwardly thereof in a radial direction there are provided a. number of guide and slippage preventing vanes 28. The vanes 28, preferably four in number and equally spaced about the inner wall of the tube 2|, extend downwardly therein to a similar number of similarly spaced discharge tubes 29 in the primary separation chamber 25. Tubes 29 are supported directly below the vanes 28 within and sealed to openings in the upper portion of the frusto-conical wall 23 of the primary separation chamber 25.

The tubes 29 extend inwardly and downwardly toward the central portion of the primary separation chamber to afford a passage means for the escape of the lighter fractions of primarily separated material from within the primary separation chamber 25 to an intermediate zone of the secondary separation chamber 22. Such intermediate zone comprises in substance the neutral zones" of the final separation chamber in the preferred embodiment of this invention. The inward extension of tubes 29 is such as to prevent the primarily separated and partially concentrated heavier fractions of the primarily separated material from escaping from the chamber 25 through the tubes 29 with the lighter fractions of the primarily. separated material. Such escape is prevented by extending the tubes 29 inwardly from the outer peripheral wall 23 a suflicent distance so that the inner ends of the tubes 29 extend through the layer of primarily concentrated heavy fraction of material, such as coagulated protein in the instance of sour cream, which separates out from the remaining liquid in the primary separation chamber and normally, due to centrifugal force, tends to cling to the outer peripheral wall 23. In the preferred embodiment of this invention the tubes 29 extend through the wall 23 to a point within the primary separation chamber 25 located a distance from the axis of the tube 2| less than the length of the radius of the tube 2| immediately above the primary separation chamber 25.

The materials flowing through the passage tubes 29 are discharged into the outer centrifugal chamber 22 through the passages 3|) formed by alined openings in the frusto-conical stratifying and separating disks 3|. The disks 3| are maintained in radial alinement by the slippage pre' venting and spacing vanes 32 formed on the outer periphery of the tube 2| The disks 3| are supported in spaced relation in the conventional manner upon the outer surface of the frusto-conlcal wall 23 of the primary separation chamber 23.

The passages 33 are spaced from the axis of rotation of the primary and secondary separation chambers 25 and 22 a radial distance approximately equal to the radial depth of the lightest fraction of the final separation within the outer and final separation chamber 22. In the practice of the invention as contemplated in its preferred form, such lightest fraction of separation would consist of concentrated butter fat. The outer surface of the layer of concentrated butter fat within the final separation chamber 22 in a centrifugal separation device, as illustrated in the accompanying drawing, would commonly be referred to as the neutral zone of the separating device.

The disks 3| are locked in operative position by a frusto-conical dividing 'wall 33 formed similarly to the disks 3| but devoid of the openings which in the disks 3| form the passages 30. The dividing wall 33 extends outwardly radially slightly beyond the outer periphery of the disks 3|. Similar to the disks 3| the dividing wall 33 is maintained in position by the vanes 32 and compressed against the stacked disks 3| by the slippage preventing and compression vanes 34 depending from the inner surface of the upper wall It of the outer rotor |3.

Formed integrally with the dividing wall-33 and defining the upper restricted opening therein, there is provided an upwardly extending tubular element 35. The element 35 extends upwardly beyond the ring dam l3 and intermediate the ring dam l9 and the lnfeed tube 2 I, thereby forming with these elements the inner and outer annular passages 33 and 31 for the discharge of the lightest and intermediate fractions of the secondary or final separation. These lightest and intermediate fractions of final separation in the practice of the invention in the separation of sour cream would consist of concentrated butter fat and skim-milk.

The relative proportions as to height and diameter of the tubular neck l3, tubular element 35 and the ring dam l3 which form the discharge passages 36 and 31 are such as to secure the appropriate static heads of the separated materials being discharged from the separating device through passages 36 and 31. The relation of the various proportions of the elements of the separating device one to another is, of course, in keeping with the conventional design and established theories.

In the outer peripheral wall of the primary separating chamber 25 and radially beyond the neutral zone of the secondary separation chamber 22, there are provided ports or passages 33 for the separate passage of the partially concentrated heaviest fraction of the primarily separated material to the outer zone of the secondary neutral zone of the chamber 22, without passing through the ducts '23, through which ducts the remainder of the separation products flows into some 0 the spaces defined by the stratifying disks II.

invention by the outer edge" of the lowest stratifyingdisk 3|a. which extends outwardly beyond the outer edges of the remainder of the stratifying disks 3| and which overhangs the ports 33. The

obstruction to the flow or the primarily concentrated heaviest fraction of separation permits some of the entrained lighter materials, such as butter fat in the instance of the separation of.

sour cream, to escape therefrom and travel up- :gardly and inwardly toward the axis of rotaon. I

To permit the discharge of the concentrated heaviest fraction of separation from the outer centrifugal rotor |3 there are provided discharge ports 33. The discharge ports 33 may be formed in any suitable fashion. In the preferred embodiment, as illustrated in the drawing, the discharge ports 39 have been formed y hollow removable studs, each closely fitted into an opening in the outer periphery of the rotor l3 at its greatest diameter. The studs l3 are provided with suitably enlarged heads on their inner ends to thereby maintain them'in proper operative position. The provision of the ports 33 in such removable studs enables the ready exchange of one set of discharge port studs for another set of studs having either larger or smaller discharge ports 39 as may be required in view of the capacity" of the centrifugal separating device.

In the preferred embodiment of the invention there are four passages 29, four ports 33 and four ports 39. The passages 23 and the ports 33 and 33 are symmetrically arranged circumferen ially of the separating .device and positioned a the greatest possible angular rotation with respect to one another. In the drawing and for the purpose of clarity of illustration only, the passages 23, ports 33 and the ports 33 have all been shown as being co-planar.

The ports 33 need only be of sufficient diameter topermit the ready flow of the primarily concentrated heavy fraction of separation from the primary separation chamber 25 into the final separation chamber 22. However, due to the fact that the outer peripheral portion of the final separation chamber 22 is normally filled with the intermediate fractions of separation, which, in the preferred practice of the improved process, would consist of skim-milk, and, in view of the fact that in the preferred embodiment the ports 33 are positioned outwardly beyond the neutral zone, there is no appreciable tendency of the lighter and intermediate fractions of primary separation to flow from the primary separation chamber 25 through the ports 38 into the final separation chamber 22. For this reason the provision of the ports 33 will not interfere with or decrease the efliciency of the separation and concentration of the lightest and intermediate fractions of separation which normally take place in-between the separation of the stratifying disks 3|. V

The ports 33 are, however, preferably only of such a total capacity as to permit the flow only of the finally concentrated heaviest fraction of separation and entrained foreign matter, together with suflicient quantities of the intermediaaaaaoo 7 1 ate fractions of'separation, and as to maintain the free discharge of the heavy concentrated materialthrough the ports 39. The ports 35 should, however, not be of such a capacity as to permit the lowering of the level of the liquid in the discharge passage 51 below the ring dam is.

It. should be understood that the improved separator and concentrator according to the present invention may be embodied in various structural modifications from that shown in the drawing. The preferred embodiment has been described as a cream separator and concentrator. Likewise the improved process, which has been referred to asa milk or cream separation and concentration process, may also be practiced in connection with the separation of various other liquids. The improved process will be described in connection with the separation and concentration of sour cream containing coagulated proteins and the products-of neutralization of acids normally present in the sour cream.

- In the separation of sour cream in a device as shown in the drawing, the cream is supplied to the mouth of the infeed tube 2| and flows downwardly therethrough in engagement with the rapidly rotating vanes 28. The vanes 28 cause the cream to rotate with the infeed tube 2!,

thereby commencing the centrifugal separation.

and concentration of the readily separable heavy fraction of separation, i. e., the coagulated proteins and semi-solid heavy products of neutralization, as well as undissolved neutralizing materials, present in the sour neutralized cream.

The coagulated proteins, the heavier products of neutralization and in some instances undissolved neutralizing materials commence to concentrate along the inner surface of the wall of the infeed tube 2i and pass downwardly into the primary separation chamber 25 in the form of a layer in close proximity to the inner surface of the wall 23 of the chamber 25. This layer of heavy materials, 1. e., coagulated proteins and extraneous matters, concentrates in the outer peripheral portions of the primary separation chamber 25. The lighter fractions of the primary separated sour cream within the chamber 25 are forced inwardly and flow toward the cen-. tral portion of the chamber 25 more remote from the wall 23 than the layer of partially concentrated and coagulated proteins and products of neutralization.

The lighter fractions of the previously separated sour cream, which consist primarily of butter fat, skim-milk and unseparated coagulated proteins, pass from the chamber 25 through the passages 29 into the passages 30 from which they are distributed into the laminar spaces intermediate the stratifying disks 3|. The drawing clearly indicates that the aligned groups of passages 30 are each positioned above the discharge end of an associated passage 29. In the laminar spaces intermediate the disks 3i the butter fat or lightest fraction of separation is concentrated and separated from the skim-milk or intermediate fraction of separation. The skim-milk, together with any unseparated coagulated protein which is heavier than the separated butter fat, flows outwardly through-between the disk 3i into the outer peripheral portion of the outer and final separation chamber 22. The concentrated butter fat is forced upwardly and inwardly through-between the disks 3| toward the axis of rotation and into the cream discharge passage 36.

, The concentrated cream or butter fat, just as in the conventional cream separator, rises in the cream flow space along the outer surface of the ini'eed tube 2| into the dividing tube 55, to be discharged through the cream discharge passage 38 by overflowing the upper edge of the tube 55. v

The greater portion of the skim-milk flows from the outer portion of the rotary chamber 22 through-between the dividing wall 53 and the upper wall I! of the outer rotor i5 into the skimmilk discharge passage 31 formed between the tube I5 and the neck ll of the outer wall I and is discharged over the ring dam ll.

Substantially all coagulated protein or other heavy extraneous foreign matter which was not primarily separated in the primary separation chamber 25 will be separated in the final separation chamber 22 and flow outwardly to the outer peripheral portions of the secondary separation chamber 22 farthest removed from the axis of rotation. It should, however, be noted that the great majority of the heaviest fraction of separation, which in the case of sour. cream consists of coagulated proteins and the heavy products of neutralization, is primarily separated from the remainder of the cream in the primary separation chamber 25.

The primarily concentrated coagulated protein and other heavy products of primary separation are separately discharged from the primary sep-,

and concentration whereby such products as sour H I cream and other like products which contain materials tending to clog flow passages within the device may be efllcientiy separated without the necessity of frequently discontinuing the separation or concentration operation andremoving the accumulated materials from within the separating device.

The invention is hereby claimed as follows:

1. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber.

2. In a bowl for a centrifugal separator, combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary eparation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, and a second passage extending from within saidprimary separation chamber to an intermediate zone of said final separation chamber, said second passage extending from within said primary separation chamber from a point located a distance from the axis of said tube less than the radius of said tube immediately above said primary separation chamber.

3. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, said outer zone being spaced outwardly of the neutral zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber.

4. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber 'surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, said outer zone being spaced outwardly of the neutral zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said second passage extending from within said primary separation chamber from a point located a distance from the axis of said tube less than the radius of said tube immediately above said primary separation chamber.

5. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, said outer zone being spaced outwardly of the neutral zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said intermediate zone constituting in substance the neutral zone of said final separation chamber.

6. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer -periphery of said primary separation chamber, a

first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, said outer zone being spaced outwardly of the neutral zone of said final separation chamber, 'a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said intermediate zone constituting in substance the neutral zone of said final separation chamber, and said second passage extending from within said primary separation chamber from a point located a distance from the axis of said tube less than the radius of said tube immediately above said primary separation chamber.

7. In a bowl for a centrifugal separator, the combination 01, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, and a discharge port in the outer periphery of said final separation chamber.

8. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said second passage extending from withinsaid primary separation chamber'from a point located a distance from the axis of said tube less than the radius of said tube immediately above said primary separation chamber, and a discharge port in the'outer periphery of said final separation chamber.

9. In a bowl for a centrifugal separator, the

combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube, a final separation chamber sur rounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, said outer zone being spaced outwardly of the neutral zone of said final separation chamber, a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said intermediate zone constituting in substance the neutral zone of said final separation chamber, and a discharge port in the outer periphery of said final separation chamber.

10. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube formed of an expanded portion of said tube. a final separation chamber surrounding said primary separation chamber and assaaoe extending radially substantially beyond the outer periphery of said primary separat on chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber. said outer zone being spaced outwardly of the neutral zone of said final separation chamber, a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said intermediate zone constituting in substance the neu-' tral zone of said final separation chamber. said second passage extending from within said primary separation chamber from a point located a distance from the axis of said tube less than the radius of said tube immediately'above said primary separation chamber, and a discharge port in the outer periphery of said final separation chamber.

- 11. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube, a final separation chamber sur rounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber.

12. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said second passage extending from within said primary separation chamber from a point located a distance from the axis of said tube less than the radius of said tube immediately above said primary separation chamber.

13. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral portion of said primary separation chamber to an outer zone of said final separation chamber, said outer zone being spaced outwardly of the neutral zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of.

said final separation chamber.

14. In a bowl for a centrifugal separator, the combination of, a hollow centrally positioned tube, a primary separation chamber at the lower end of said tube, a final separation chamber surrounding said primary separation chamber and extending radially substantially beyond the outer periphery of said primary separation chamber, a first passage through the outer peripheral'portion of said primary separation chamber to an outer zone ofsaid final separation chamber, said outer 12 zone being spaced outwardly of the neutral zone of said final separation chamber, and a second passage extending from within said primary separation chamber to an intermediate zone of said final separation chamber, said second passage extending from within said primary separation chamber from a point located a distance from Y the axis of said tube less than the radius of said tube immediately above said primary separation chamber.

l5.'In a device of the type described for the centrifugal separation of material into lighter and heavier fractions of separation, the combination of a final outer rotary centrifugal separation chamber and a primary inner rotary centrifugal separation chamber, said chambers having a common axis of rotation, means for the introduction of material to be separated into the inner rotary centrifugal separation chamber, a first passage means for the passage of lighter fractions of the primarily separated material and unseparated heavier fractions of the material subjected to primary separation from said inner rotary centrifugal chamber into the outer rotary centrifugal chamber, a second passage means for the passage of heavier primarily separated fractions of the material from said inner rotary centrifugal chamber into said outer rotary centrifugal chamber, the entrance to said second passage means being positioned a greater radial distance from said axis of rotation than the entrance to said first passage means and radially beyond the radial depth of the space in said outer rotary centrifugal chamber normally occupied by the lighter fractions of separated material, and port means in the outer periphery of said outer rotary centrifugal separation chamber for the discharge of material therefrom, said port means being spaced from said axis of rotation a greater radial distance than the distance between said second passage and said axis of rotation.

16. In a device of the type described for the centrifugal separation of material into lighter.

and'heavier fractions of separation, the combination of a final outer rotary centrifugal separation chamber and a primary inner rotary centrifugal separation chamber, said chambers having a common axis of rotation, means for the introduction of material to be separated into the inner rotary centrifugal separation chamber, a first material within said outer rotary centrifugal separation chamber, second passage means for the passage of material from the peripheral portion of said inner rotary centrifugal separation chamber into said outer rotary centrifugal separation chamber, the entrance to said second passage means being positioned a greater radial distance from said axis of rotation than the entrance to said first passage means, and a third passage means for passage of material through the outer periphery of said outer centrifugal chamber, said third passage means being of such a capacity as to permit the passage of only a portion of the heavier fractions of the separated materials therethrough.

17. In a device of the type described for the centrifugal separation and concentration of material into light, intermediate and heavy fractions of separation, the combination of a first outer rotary centrifugal separation chamber and a primary inner rotary centrifugal separation chamber, said chambers having a ommon axis of rotation, first means for the passage of light and primarily unseparated light, intermediate and heavy fractional components of the material from said inner centrifugal rotary chamber remote from the periphery thereof into said outer centrifugal rotary chamber, second means for the passage of heavy primarily separated fractions of the material from the outer peripheral portion of said inner rotary centrifugal chamber into said outer rotary centrifugal chamber, the entrance to said second means being positioned a greater radial distance from said axis of rotation than the entrance to said first means, and means for discharging light, intermediate and heavy fractions of separation from said outer rotary centrifugal chamber, the means for so discharging the heavy fraction of separation comprising a port positioned in a portion of said outer centrifugal chamber having the greatest diameter, said port and said second means being positioned radial distances from said axis of rotation greater than the radial depth of the space normally occupied by the lighter fractions of separation within said outer centrifugal separation V chamber.

18. A device for the centrifugal separation of cream containing coagulated protein into light and intermediate and heavy fractions of separation comprising, in combination, a secondary centrifugal rotary separation chamber, discharge passage means in the wall of said secondary separation chamber positioned in the portion thereof having the greatest diameter. a primary centrifugal rotary separation chamber centrally positioned within said secondary separation chamber and adapted to rotate therewith and effect a primary concentration of coagulated protein therein, a plurality of centrally positioned stratifying disks within said secondary separation chamber said disk having distributing passages therethrough positioned at the neutral zone of said secondary separation chamber, flow passage means for the fiow of cream through the wall of said primary separation chamber into said distributing passages, said fiow passage means and said distributing passages being so arranged as to permit the flow of cream subjected to primary separation into the neutral zone of the spaces between said stratifying disks from within said primary separation chamber, the inner end of said flow passage means being positioned remotely from the periphery of said primary separation chamber, and port means for the passage of concentrated coagulated protein through the wall of said primary separation chamber, said port means being outwardly of said neutral zone and being so arranged as to permit the flow of primarily concentrated coagulated protein separately from the remainder of the cream out of said primary separation chamber to said discharge passage.

19. A device according to claim 18 in which one of said stratifying disks is .so constructed and arranged as to obstruct the flow of the previously coagulated protein from said port to said discharge passage.

20. In a centrifugal separator for the separation and concentration of sour cream into coagulated protein, skim-milk and concentrated butter fat, a final centrifugal separation chamber for the final separation and concentration of sour cream into coagulated protein, skim-milk and concentrated butter fat, a primary centrifugal separation and concentration chamber for the primary separation and concentration of coagulated protein from sour cream, said primary separation and concentration chamber having a cream inlet and being positioned within said final separation chamber and adapted to rotate therewith, stratifying disks within said final separation chamber, a first coagulated protein discharge passage through the wall of said final separation chamber in a portion of the wall having the greatest diameter, skim-milk outlet and concentrated butter fat outlet in the upper wall of said final separation chamber, a cream discharge passage extending through the wall of said primary separation chamber and adapted to discharge cream which has been subjected to primary separation into the spaces between said stratifying disks at the neutral zone of said final centrifugal separation chamber from a portion of the interior of said primary separation chamber remote from the outer peripheral wall thereof, and a second coagulated protein discharge passage for discharging primarily separated and concentrated coagulated protein from the outer portions of said primary separation chamber into said final separation chamber at a point beyond the neutral zone of said final centrifugal separation chamber, said first coagulated protein passage being of such capacityas to permit the discharge therethrough of sufilcient skim-milk portion of the separated sour cream as to aid in the discharge of coagulated protein from said final separation chamber through said first coagulated protein discharge passage.

21. The process in a centrifugal separator having primary and secondary rotary centrifugal separation chambers of centrifugally separating and concentrating cream containing coagulated protein, comprising the steps of subjecting the cream to primary centrifugal separation in the primary separation chamber sufficiently to separate and concentrate the readily separable coagulated protein from the remainder of the cream, discharging the primarily concentrated coagulated protein and the remainder of the primarily separated cream from the primary separation chamber into the secondary separation chamber, the concentrated coagulated protein being discharged from said primary separation chamber into said secondary separation chamber separately from the remainder of the primarily separated cream and into a zone of said secondary separation chamber outwardly of the neutral zone of said secondary separation chamber, subjecting the remainder of. the primarily separated cream and the coagulated protein concentrate to secondary separation and further concentration separately within the secondary separation chamher, and discharging the secondarily concentrated coagulated protein from the zone of greatest centrifug'al separation of the secondary separation chamber.

22. The process of clarifying a liquid containing extraneous matter in a centrifugal separator having primary and secondary separation chambers, comprising the steps of subjecting the liquid to primary centrifugal separation in the primary separation chamber sufilciently to concentrate the readily separable extraneous matter from the remainder of the liquid, discharging the concentrated readily separable extraneous matter and all of the remainder of the primarily separated liquid from the primary separation chamber into 15 the secondary separation chamber, said concentrated extraneous matter being discharged from said primary separation chamber into said secondary separation chamber into a zone outwardly of the neutral zone of said secondary separation chamber and separately from the remainder of the primarily separated liquid, subjecting the remainder of the primarily separated liquid and the primarily separated extraneous matter to secondary separation and concentration separately within the secondary separation chamber, and

discharging the secondarily concentrated extraneous matter from the zone 0; greatest centrifugal concentration of the secondary chamber.

INGIE J. LUNDAL.

. 16 aaraaancns crran The i'ollowing references are of record in the file of this patent:

UNITED STATES PATENTS 

